This application claims the benefit of and priority to GB Application No. 1911923.9, filed on Aug. 20, 2019, the contents of which is incorporated herein by reference in its entirety.
The present invention relates to apparatus for weighing a person with reduced mobility.
There are times when it is appropriate or necessary to weigh a person. Conventionally this is done by the person standing on a set of scales and taking a reading from the scales. However, for a person with reduced mobility, it can be difficult or impossible to stand up for a prolonged period of time. It may also be impossible for the person to stand without assistance, or without involuntary movement, and so on, which can prevent an accurate weight measurement being taken.
It might be envisaged to employ means to weigh the person while sitting down, but moving from a sitting to a standing position afterwards (and potentially vice versa) can for a person of reduced mobility be more challenging than maintaining a standing position, even with assistance from a helper. These difficulties can outweigh the benefits of taking the weight measurement in a sitting position.
The present invention aims to address problems in the art such as (but not limited to) those mentioned above.
According to a first aspect of the present invention, there is provided apparatus for weighing a person with reduced mobility (with or without assistance), the apparatus comprising: a seat portion; scales for weighing the person when sitting on the seat portion; and a lifting mechanism to assist the person in standing up from the seat portion.
Accordingly the apparatus can provide the advantages of weighing the person in a sitting position without suffering the corresponding disadvantage of the person with reduced mobility having to transition themselves from a sitting to standing position. It can also assist a helper in transitioning the person from sitting to standing and vice versa.
The scales may comprise at least one load cell of any appropriate type, or any other means of recording an applied weight of the person. Essentially any weighing device may be used if it is able to fit within the apparatus and accurately record the weight of a person sitting on the seat portion.
Preferably the lifting mechanism is powered so that, in use, it urges the person to the standing position. The apparatus may be self-powered, powered by an operator, or powered by an external power supply (such as the mains, for example), or any appropriate combination of the above. Alternatively the lifting mechanism may be unpowered, in which case there may be provided means for manually operating the lifting mechanism. The lifting mechanism may include at least one handle or other lifting device to allow an operator to control the position of the seat portion.
Preferably the lifting mechanism acts on the seat portion and the seat portion in turn urges the person to a standing position, such that the lifting mechanism is operable to move the centre of gravity of the seat portion in an upwards direction and/or the lifting mechanism is operable to rotate seat portion so as to raise the rear of the seat relative to the front of the seat. The term ‘upwards direction’ does not imply an absolutely vertical direction but a direction having at least an upwards component. The term ‘rear’ is as would be regarded as the rear of the seat portion when the person is sat on it.
The lifting mechanism may be operable in reverse to assist the person in sitting down on the seat portion.
Preferably the lifting mechanism is operable to move the seat portion between a sitting position, for engaging with the person in a sitting position, and a standing position, for engaging with the person in a standing position. In the sitting position, the seat portion is substantially horizontal and engages with the apparatus in a substantially vertical direction, facilitating accurate weighing of the person sat on the seat portion. Normally, in the sitting position, the seat portion contacts the scales and does not contact the lifting mechanism. Preferably the apparatus is operable for an applied weight range (that is, typically the weight of the person) of between 0 kg and at least 200, 250, 300, 350 or 400 kg.
In contrast to the above, in the standing position, the seat portion preferably contacts the lifting mechanism. The seat portion may be held in place by the lifting mechanism, may rest on it, and/or may be freely moveable away from the lifting mechanism. This may be true both in the sitting position and in the standing position. The term ‘held in place’ may connote the movement of the seat portion being restricted or resisted by the lifting mechanism, preferably such that the seat portion resists the (inadvertent or otherwise) application of forces on the seat portion by the person in the standing position unless and until the lifting mechanism is operated (or action is otherwise taken) to transition the seat portion to the sitting position. In the sitting position, the seat may typically be held in place but also have an allowed range of movement.
The seat portion typically resists forces from the person in the sitting position as well, typically by transmitting the forces to the set of scales on which the seat portion normally rests in that position. In another operating mode the weight of the person applied to the seat portion in the standing position can be used to cause the seat portion to return to the sitting position.
Preferably the seat portion has a first range of movement from the standing position to the sitting position, the lifting mechanism has a second range of movement from the standing position to the sitting position, and the second range of movement is greater than the first, such that when the seat portion reaches the end of its movement and comes to rest on the scales, the lifting mechanism is operable to continue its movement into clearance of the seat portion. ‘Moving into clearance’ preferably has the normal meaning in the art of something moving into a position where it is unable to come into contact with another object or part of an object.
Preferably the lifting mechanism comprises a lifting member which engages with the seat portion at an engagement region, and the apparatus further comprises at least one actuator guide for restraining the lifting member at the end of a movement of the seat portion to the sitting position. This can be useful, for example, if continuing to move the lifting member would cause the lifting mechanism to come into contact with the seat portion again.
Typically the seat portion may rotate about a seat pivot axis between a first angle corresponding to the sitting position and a second angle corresponding to the standing position, in which case preferably the lifting member is a linearly extendable member, such that reciprocating motion of the extendable member is converted into a rotation of the seat portion about the seat pivot axis. In some cases a rotational input could instead be applied.
In certain embodiments, the freedom of movement of the seat portion varies in dependence on the rotation of the seat portion about the seat pivot axis. The freedom of movement is typically but not necessarily freedom of movement about the seat pivot axis. The freedom of movement may also include linear movements in any appropriate direction, for example to allow adjustment of the seat portion.
In one aspect, seen for example in an alternative embodiment described below, the lifting mechanism comprises a lifting member which (again) engages with the seat portion at an engagement region and pivots about a further pivot axis located in the engagement region, wherein the further pivot axis is parallel to the seat pivot axis, such that the angle subtended between the lifting member and the seat portion varies as the seat portion moves between the sitting position and the standing position, and wherein the freedom of movement of the seat portion varies in dependence on the subtended angle.
In any of the above aspects (or otherwise) the lifting mechanism may comprise an actuator, piston assembly, gas strut, or any other appropriate mechanism for causing axial movement of an appropriate lifting member. A gas strut may have preloading constraints which may cause difficulties with operation of the device.
In other aspects, other means of applying a force or a torque may be used. For example a torque may be applied directly about the seat pivot axis (for example using an electric motor and the like, possibly applied via appropriate gearing and, if necessary, a clutch) so as to cause direct rotation of the seat portion.
The lifting member is preferably constrained within an aperture in an actuator link plate attached to the seat portion, the aperture defining the linear freedom of movement of the seat portion relative to the lifting member. The aperture may be shaped such that rotation of the lifting member relative to the seat portion causes the lifting member to be constrained by different parts of the aperture, preferably wherein different parts of the aperture permit different degrees of freedom of the seat portion relative to the lifting member. By virtue of these features or otherwise, the further pivot axis may in some cases be a virtual pivot, which the lifting member effectively rotates around but does not contact or extend fully towards. A plurality of actuator link plates may be provided, for example one on either side of the lifting member.
The internal aperture preferably acts as a cam surface, and the lifting member interacts with the cam surface via a follower member, which may for example be a bar extending transverse to the aperture and attached to the lifting member.
In the case where the aperture defines different degrees of freedom (or otherwise), the lifting mechanism may be operable, when moving the seat portion into the sitting position, to retract the lifting member until it urges the seat portion into the sitting position, and then to extend the lifting member again by an amount sufficient to ensure that the lifting member no longer contacts the seat portion but the seat portion remains in the sitting position. This can ensure that there is good separation between the lifting member and its connection to the seat portion while weighing is taking place, so that the seat portion can displace vertically without coming into contact with the lifting member (which could affect the weight measurement).
Preferably the apparatus further comprises at least one rest selected from: a back rest, at least one foot rest, and at least one arm rest. In that case, said at least one rest is preferably moveable between a deployed position and a stowed position, wherein when said at least one rest is in the stowed position, unobstructed access is provided to the seat portion from the front and from at least one side of the apparatus. Preferably wheelchair users can directly access the seat portion from at least one side of the apparatus.
Preferably the said at least one rest is able to rotate at least 90, 120, 180 or more degrees, and is preferably able to rotate so as to be at least flush with the apparatus such that said at least one rest does not protrude substantially forwards or sideways from the apparatus. The foot rests for example may rotate at least 120, 150, 160 or 180 degrees around a vertical axis. The arm rests for example may rotate at least 90, 120, 150 or 180 degrees around a horizontal axis such that they do not obstruct the seat portion either from the front or from the sides of the apparatus.
The back rest is preferably independent of the seat portion but may in some cases be attached so that the entire back rest and seat portion assembly moves as one.
Although various aspects and embodiments of the present invention have been described separately above, any of the aspects and features of the present invention can be used in conjunction with any other aspect, embodiment or feature where appropriate. For example apparatus features may where appropriate be interchanged with method features. References to single entities should, where appropriate, be considered generally applicable to multiple entities and vice versa. Unless otherwise stated herein, no feature described herein should be considered to be incompatible with any other, unless such a combination is clearly and inherently incompatible. Accordingly, it should generally be envisaged that each and every separate feature disclosed in the introduction, description and drawings is combinable in any appropriate way with any other unless (as noted above) explicitly or clearly incompatible.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:
The preferred embodiment provides an apparatus (typically a weighing chair) for weighing people with reduced mobility. Various aspects and features of the apparatus will now be described.
Other arrangements are of course possible. For example, the pivot point 206 may be connected to or via the load cell(s) directly, or the lifting mechanism may be configured such that the pivot point 206 is only a virtual pivot, and the seat portion 202 does not physically connect to it.
The law of cosines (c2=a2+b2−2ab cos C) can be used in conjunction with a sensed or known extension of the linearly extending member 306, or the law of sines (sin(A)/a=sin(B)/b=sin(C)/c) can be used in conjunction with any measured or known angle θn, to determine all remaining angles. This can be used in particular to determine the angle θ3 for each moment as the seat portion moves from sitting to standing position (which transition can be expressed with the ranges LSITTING<L2<LSTANDING, or θSITTING<θ2<θSTANDING).
Notwithstanding the above, the key point is that angle θ3 subtended between the linearly extending member 306 and the seat portion 302 varies predictably as the seat portion transitions between sitting and standing positions (and vice versa). Angles θ1 and θ2 also varies predictably as the seat portion transitions between positions.
The term ‘actuator’ is used in a general sense to connote any device capable of applying a force or causing movement on demand, and may, for example, include devices capable of applying a torque or causing a rotation. The actuator 516 may nevertheless comprise an actuator within the narrow sense of the term in the field of mechanical engineering. The actuator 516 may alternatively or additionally include a piston arrangement, gas strut (with appropriate preloading), electric motor with appropriate gearing and translation from rotational to linear movement as necessary, magnetic actuation, pneumatic or hydraulic mechanisms as appropriate for any given application.
Preferably a strain (or other) load cell is used as the scales (that is, simply to weigh the person). Appropriate zeroing and/or calibration may be provided, for example periodically to weigh the seat portion without a person sat on it (either manually or automatically). Other types of scales are of course possible, including devices based on magnetic, inductive, mechanical, optical, or piezoelectric principles, and so on.
In the present embodiment two separate connecting plates 606 are provided with two separate but matching apertures 608, and the rod 616 passes transversely between both, threading through a hole in the distal end of the member 614 so as to secure it in place and prevent out of plane rotations (as pictured in
It will be appreciated the weight from the seat and/or the weight of a user urges the seat 602 and correspondingly the plates 606 onto the transverse bar 616. In the standing position of the seat 602 and when the actuator is retracting the seat towards the sitting position (but not yet fully retracted), the bar 616 forms a pivot at the top of the aperture 608. The shape of the top of the aperture permits the bar 616 to roll freely without causing any displacement between actuator 610 and seat 602. When the actuator 610 comes to the end of its travel, the transverse bar 616 moves into clearance from the aperture 608 and consequently seat 602, as is described below.
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Thus a mechanism is provided which can engage and disengage a lifting mechanism with a seat portion (or other appropriate drive object) merely by extending and retracting a member. This can provide a relatively low cost system for weighing a person with reduced mobility.
In the present embodiment two separate connecting plates 906 are provided with two separate but matching apertures 908, and the rod 916 passes transversely between both, threading through a hole in the distal end of the member 914 so as to secure it in place and prevent out of plane rotations (as pictured in
It will be appreciated from
In the expanded region, there is a ‘dead zone’ or hysteresis, where the rod attached to the extending member can be moved into the middle of the aperture and thereby avoid all contact with the aperture or, by extension, the seat portion. As before, this can allow weighing without any external influence from the lifting mechanism. More generally, this mechanism can provide a way to vary the freedom of movement of the seat portion in dependence on its rotation without any complicated extra components to allow such a decoupling (or indeed any extra components whatsoever).
Brakes may be provided and applied to the wheels as appropriate. A hollow in the back rest provides appropriate cable management within easy reach, and a control panel allows both weighing operations and activation of the lifting mechanism. Other arrangements are of course possible.
Various features have been described above in relation to a weighing chair, but variants are possible in which the operative elements described above are provided in alternative forms. Appropriate modifications may be made for example to incorporate the above-mentioned features into a hospital bed (in-patient or out-patient), into an otherwise ordinary chair, sofa or bed, and so on. The relevant object may be mobile (for example have wheels) or not, and may for example be suspended from a ceiling rather than stand on the floor. The concepts described herein can of course also be used to weigh things rather than people, or for any other appropriate purpose.
It will be appreciated that further modifications may be made to the invention, where appropriate, within the spirit and scope of the claims.
Number | Date | Country | Kind |
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1911923.9 | Aug 2019 | GB | national |